#include<stdio.h>
#include<ctype.h>
int lmabda(int c)
{
if(c>='A'&&c<='M'){
 return c+'S'-'F';  // +13
}
else if(c >='N'&&c<='Z')
{
return c+'F'-'S';   //-13
}
else if(c>='a'&&c<='m')
{
    return c+'S'-'F'; // +13
}
else if(c >='n'&&c<='z')
{
   return c+'F'-'S';  //-13
}
else
    return c;
}
int main(){
    char a;
    putchar(a);
    
    printf("输入一个字符：%c\n",a);
    a=tolower(getchar());
    printf("字符：%c\n",a); 

/* char b;
putchar(b);
printf("加密前的字符：%c\n",b);
b=lmabda(getchar());
printf("加密后的字符：%c\n",b);   
     */
    
    return 0;
}
